I've received a SNES to install a supercic mod in, but unfortunately it doesn't boot any games. So I tried a burn-in test cartridge, and initially that didn't give anything but a black screen either. I verified that some voltages are present on all chips and decided to touch up the PPU's and CPU. Tested the burn-in cartridge again and now it definitely booted, but the graphics were all black and white and garbled up, but I could see some resemblance to what it was supposed to display. When I hit start the screen went black and after a few seconds the controller test menu game up, and I could see some graphical activity in the area where it lights up the button that you need to press for the test to advance.I then reset the console and tried the other menus but they caused the console to hang. After a few minutes I couldn't get the cart to boot anymore either.

I have spare super famicoms for replacement chips. I'm just not sure which one I should try replacing first, given the above. The CPU definitely runs (well.. ran for a bit), but that's about all I can deduce. Dogp's repair logs pretty much indicate CPU the most common culprit, but my symptoms don't match any of the repairs he worked on. Anyone wanna weigh in on what I should replace first?Also, are all CPU and PPU1/PPU2 drop-in replacements for each other?

Most SHVC-CPU-01 2/1/3 units are not fixable. If one chip is damaged, they might all be damaged.

At any rate "black and white and garbled up" suggests your connection first. This is the same kind of effect you would see if you connect the composite or the Y (luma) pin to the Green pin on a 480p component input or only the Y pin on a S-video input. If that's not it, it's the PPU's output doing something similar (eg no red or blue component from PPU2 to S-ENC), the garbled parts are likely between the CPU and the PPU1 or between the PPU's and the video memory.

A screenshot would be helpful, though there is no guarantee that a SNES/SFC can be fixed, the fact that you can boot a game at all suggests that it may be fixable. Systems that just "black screen" when powered always blame the CPU or the CIC chip, but there's no way to tell if all the chips are good.

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I've fixed one sometime ago with a similar problem.The video was all black and white and distorted.It was a weird trancodification circuit at the s-enc and a capacitor on the composite video's output.I remade the transcodification, exchange the capacitor and all went fine.Hope this helps.

You didn't say ... did all of the explicit tests in the burn-in cartridge get a pass? (Or can you not tell, because the video is only barely functional?)

The tests crashed the console. I managed to start the bottom test #5 (forgot what it was called) which usually shows a bunch of fail/pass messages, but I couldn't tell from the output whether tests passed or not. It definitely crashed during the tests though.

I've fixed one sometime ago with a similar problem.The video was all black and white and distorted.It was a weird trancodification circuit at the s-enc and a capacitor on the composite video's output.I remade the transcodification, exchange the capacitor and all went fine.Hope this helps.

Wow, that does look similar indeed. Additionally the guy who sent it to me told me he also got a black screen but then left the console on for some minutes (as to charge the capacitors) and then it started working. I'll try this first!

Recapping didn't help so I'll try replacing the CPU next. I found one that wasn't so nicely desoldered, bent legs and it doesn't sit entirely flat. But with some patience and fine tweezers it'll work, if not I'll have to sacrifice a dirty yellow cheap super famicom.

Honestly, I'm going to say (based on the color, and the right-hand-side of the screen) that the problem lies in PPU2. It's difficult to really say one way or the other because if the CPU works enough to boot, then the problem is likely not the CPU, but rather the connection between the CPU, PPU's and the video memory. Like at the moment it looks like maybe some of the address lines aren't connected to the video ram so what is ending up in it is garbage.

_________________I come from the net. Through systems, peoples and cities to this place.

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